Arrangement for controlling special indications of distant signals



March 11, 1952 P. Fr-HOLDEN 2,588,836

ARRANGEMENT FOR CONTROLLING SPECIAL INDICATIONS OF DISTANT SIGNALS Filed June 5, 1947 2 SHEETSSHEET .1

v QINVENfOR. 7i 1? Holden BY HIS ATTORNEY March 11, 1952 P HOLDEN 2,588,836

F. ARRANGEMENT FOR. CONTROLLING SPECIAL INDICATIONS OF DISTANT SIGNALS Filed June 5, 1947 2 SHEETS-SHEET .2

N m/ 31- E 3 INVENTOR.

Pbz'llg'u Holden. BY

HIS arwmr Patented Mar. 11, 1952 ARRANGEMENT FOR CONTROLLING SPE- CIAL INDICATIONS OF DISTANT SIGNALS ?hillip .F. Holden, Norfolk, Va., assignor to Westinghouse Air Brake Company, a corporation of Pennsylvania Application June 3, 1947, Serial No. 752,076 '1 Claims. (01. 24c .219.)

My invention relates to a railway signal control system, and particularly to a railway signal control system for signals for governing traffic movements in both directions over a stretcher" railway track.

For governing traific movements in opposite directions over a switch which connects a main track with an auxiliary track, manually controllable signals are commonlyprovided, which may for example, be of the color light type, and are arranged to normally display a stop indication. The signal which governstraflic movements in the facing direction over the switch may be provided with an upper arm or group of color lights for governing traiiic movements along the main track over the switch in its normal position, and with a lower arm or'group ofcolorlights for governing trafiic movements from the main track to the auxiliary track over the switch in its reverse position. For governing traffic movements approaching this signal, a distant signal maybe provided having an upper arm orgroup of color lights and also a lower arm or group of color lights for providing special indications in addition to the usual clear and approach indications.

One feature of my invention is the provision of an arrangement for controlling the special indications of the distant signal by a line circuit including a control line conductor for the opposing home signal, and an approach line control conductor.

I shall describe one form of apparatus embodying my invention, and. shall then point out the novel features thereof in claims.

The accompanying drawings, Figs. 1a and lb, when placed end to end, with Fig. la on the left, constitute adiagrammatic view showing one form of apparatus embodying my invention, in which color light-signals are employed, and in which a transfer relay is controlled to become energized if a train approaches the distant signal while one of the yellow lamps or the green lamp of the home signal is controled to be lighted, and in which the transfer relay, upon becoming energized, completes a line circuit for energizing a polarized signal relay for-controlling thespecial indications of the distant signal.

Similar reference characters refer to similar parts: in the drawings.

Referring to the drawings, a stretch of single track railway, designated by the reference character X, is shown, over which traffic movementsv may be made in either direction. Track X is con! nected with an auxiliary track Z by a switch W which. is shown in its normal position for traffic movements along. track X. Switch W isoperable, by any suitable means, to a reverse position for tram'c movements from each .of these tracks to the other. In order to simplify the drawing, each track, comprising two parallel: series of. track.

rails, is represented by a single line.

The stretch of main track X is divided by insulated joints 1- into sections oa, a-b, b--c and ce. Each of these sections is provided with a track circuit including a track relay, designated by"the reference character TR with a distinguishing numerical prefix, connected across the rails adjacent one end of the section, and a suitable source of current, such as a battery 2, connected across the rails adjacent the opposite end of'the section.

A home signal 68 havingan upper group it of green, yellow and red lamps, designated by the reference characters G, Y and R, respectively, and a lower group d of yellow and red lamps Y and R, respectively, isshown at point 1). Signal 6S governs traffic movements toward the left, .as shown in the drawing, whichI shall assume is :the westbound direction, off of :section b-c andv over section a-.b in which switch W is located; Lamp G or lamp Y of group u, upon being lighted in conjunction with lamp R of group d; directs .traffic movements over switch W in its normal position along track X, and lamp Y of group (1, upon being lighted in conjunction with lamp R of group a, directs traffic movements over switch W in its reverse position from track X to track Z.

A .distantsignal 8S, comprising an upper group a of green, yellow and red lamps. G, Y and R, respectively, and alower group d of green, yellow and red lamps G, Y andR, respectively, governs westbound traffic movements, into section b;-c toward homesignal 6S.

Trafiic movements in the eastbound direction are governed by signals 4S, 5S and. IS, each of which comprises a. single group of. green, yellow and red lamps G, Y and R,xrespectively.

.Signal 1S is controlled by a signal relay lHD, only a portion of the control circuit for which is shown including av contact, of relay 1TH. A. direction stick relay 18R, associated with, signal TS, is controlled in a well-known manner to become energized when an eastbound train enters section lTR. whilerelay 1I-IDis energized for. controlling lamp .G or lamp Y of signal is to be 0 lighted. Signal 53 is controled inpart by a relay .The upper groupu of lampsof signal 65 is con.- trolled by a home relay uiiH and by a. distant relay 6D. Relay 6D. is controled in a well-known manner by traflic conditions so that it is, energized if track .X' is unoccupied for ,a given dis.- tance west of signal 5S.v Relay.6D is therefore shown controled. by a circuit which includes a contact .50, of track. relay 5TB. similarly to the circuit for relay lHD which includes. contact 35 of track relay 'lTR. The lower group-d of the lamps of signal 6S isicontroledi by a home relay dGH. Relays, uBH and .dfiH: are controled. by a manually operable. lever 6V whichz'hasa normal 60 position nand areverse position. 1:. and byra con tact 26 which is, operated in conjunction; with; switch W so asto be. closed in avnormal position when switch W occupies its normal position and to be closed in a reverse position when switch W occupies its reverse position.

Light-out relays, designated by the reference characters SGLO and uEYLO, are energized in series with lamps G and Y, respectively, of upper group it of the lamps of signal 63, so that if either of these lamps becomes burned out, the light-out relay which is in series with it will become deenergized. A third light-out relay dtLO is energized in series with lamp Y of lower group d of the lamps of signal 68. A light-out relay u8LO is also energized in series with lamp Y of upper group a of the lamps of signal 88.

An approach locking relay, designated by the reference-character 5ALS, is shown controlled in a suitable well-known manner which is common for approach locking relays, by a back contact of home relay 5BR, so that it will be energized only if signal 58 is so controlled that its red lamp is to be lighted.

The lamps of the upper group it of signal 83 are controlled by a slow release polarized signal relay uflHD. The lamps of lower group d of signal 83 are controlled by a slow release polarized signal relay d8HD.

An approach relay, designated by the reference character 6A, is normally energized, but becomes deenergized when a westbound train approaches signal 88, and remains deenergized while section 11-0 is occupied by a train.

A transfer relay GE is normally deenergized, but becomes energized when relay BA becomes deenergized, if relay uBH or dBH is energized.

Having described, in general, the arrangement of the various parts of apparatus embodying my invention, I shall now describe the circuits and operation in detail.

As shown by the drawings, all parts of the apparatus are in the normal condition, that is, switch W is in its normal position; signals 48, 5S and 63 are indicating stop; lamp G of signal IS is lighted; upper lamp Y and lower lamp R of signal 83 are lighted; the track sections are unoccupied, and therefore the track relays are energized; each of the levers 5V and 6V is in its normal position it; relay EHD is energized "by current of normal polarity; relay uBI-ID is energized by current of reverse polarity; relays BALS, 6D, 6A, 'IHD and uSLO are energized; and relays uBH, dBH, 5HR, EGLO, uGYLO, dGLO, 6F, 18R and dill-ID are deenergized.

Relay II-ID is normally energizedby a circuit which includes contact 35 of relay 'iTR.

The circuit by which relay 5HD is energized by current of normal polarity passes from terminal IB of a suitable source of current, shown as a battery IQ, through the back point of contact 3 of relay 'ISR, front point (if contact 4 of relay II-ID, contact 5 of relay BTR, back point or 0011". tact 6 of relay 6F, winding of relay 5HD, contact I of relay STR, and the back point of contact 8 of relay 'ISR to terminal IN of the same source of current. Signal 58 is also controlled in part by manual means, which may, for example, be a relay 5HR controlled by a manually operable lever 5V similarly to the manner in which relay uBI-I is controlled by lever [W for controlling the upper group it ofthe lamps of signal 68. Although relay SI-ID is normally energized by the circuit just traced, signal 58 is normally controlled by relay 5HR to indicate stop, so that red lamp R of signal 5S is normally lighted by a circuit passing from-terminal EB of a suitable source of lighting current, shown as a battery EQ, through the back point of contact 39 of relay SHR, and lamp R to terminal EN of the same source of lighting current.

Lamp R of upper group it of the lamp of signal 68 is lighted by a circuit passing from terminal EB, through the back point of contact 9 of relay uGH, and lamp R to terminal EN. Lower lamp R of signal [is is lighted by a similar circuit, which includes the back point of contact II of relay dSH.

Relay EALS is normally energized by circuit means including a back contact 40 of relay 5HR. Relay u8HD is energized by current of reverse polarity in a circuit passing from terminal B,

through the back point of contact I2 of relay: GGLO, contact I of relay 8TB, winding of relay uBHD, contact I3 of relay ISR, contact M of relay 8TR, contact I5 of relay fiTR, contact IE of relay SALS, and the back point of contact ll of relay BGLO to terminal N. Relay uBLO is energized, and upper lamp Y of signal as is.

lighted, by a circuit passing from terminal EB, through the front point of contact I8 of relay uBHD, contact I9 of relay uSHD in its reverse.

position, winding of relay u8LO, and upper lamp Y to terminal EN. Lower lamp R of signal 88 is energized by a circuit passing from terminal EB, through the back point of contact 20 of relay d8HD, and lower lamp R to terminal EN.

Lamp G of signal IS is energized by a circuit passing from terminal EB, through the frontv point of contact 48 of relay 'IHD, contact 49 of relay IHD in the normal position, and lamp G of signal IS, to terminal EN.

Approach relay 6A is energized by a circuit passing from terminal IB, through the back point of contact 3 of relay 'ISR, front point of contact 22 of relay 'I'TR, contact 23 of relay 8TH. back point of contact 24 of relay 6F, winding of relay 6A, contact I of relay BTR, and the back point of contact 3 of relay ISR to terminal IN.

I shall assume that, with apparatus as shown in the drawing, a leverman arranges for a westbound trafiic movement over switch W in its normal position by moving lever 6V to its 1' position. I shall assume further that trafiic conditions west of signal 68 are such that relay 6D is deenergized.

With lever 6V in its 1 position and switch W in 7 its normal position, relay uGH will be energized by a circuit passing from terminal B, through contact 25 of lever 6V closed in the 1' position, contact 26 of switch W in its normal position, and

- the winding of relay uSH to terminal N. With relay uBH energized and with relay 6D deenergized, relay uGYLO will be energized and upper lamp Y of signal 68 will be lighted by a circuit passing from terminal EB, through the front point of contact 9 of relay ufiH, back point of contact II] of relay 6D, winding of relay uSYLO, and

upper lamp Y to terminal EN. Lower lamp R of signal 68 remains lighted by its circuit previously traced.

With relay BGLO still deenergized, relay uBHD' is still energized by current of reverse polarity in its circuit previously traced. Relay u8L0 and upper lamp Y of signal are therefore energized by theircircuits previously traced, and lower lamp R of signal 88 is also lighted by its circuit previously traced. I shall also assume further that a westbound train now approaches, and deenergizes relays 'ITR and 'IHD.

With relay 'ITR deenergized, the circuit previously traced for relay EA will be open at the front point of contact 22 of relay 'ITR, causing relay EA to be deenergized. With relay 6A deenergized and relay uGH energized, a circuit is completed for energizing relay 6F, this circuit passing from terminal B, through contact 21 of relay uEI-I, contact 29 of relay 6A, and the winding of relay 5]? to terminal N.

'With relay 'IHD deenergized, the circuit previously traced for relay 5HD will be open at the front point of contact 4 of relay lHD, causing relay 5HD to be deenergized.

-With relays uSYLO and SF energized, and with relays ll-ID and TTR deenergized, relay dSHD will now be energized by current of reverse polarity in a circuit passing from terminal B, through contact 30 of relay uSYLO, back point of contact 3| of relay dEiLO, front point of contact 24 of relay 6F, contact 23 of relay 8TR, back point of contact 22 of relay 'ITR, contact 32 of relay uBLO, winding of relay dBHD, back point of contact 4 of relay 'lHD, contact 5 of relay 8TB, front point of contact 5 of relay 6F, back point of contact 33 of relay dELO, and contact as of relay uBYLO to terminal N. With relay dill-ID energized by current of reverse polarity, lower lamp Y of signal as will now be lighted by its circuit passing from terminal EB, through the front point of contact 25 of relay dSHD, contact 2! of relay dGHD closed in the reverse position, and lower lamp Y of signal 88 to terminal EN. With both lamps Y of signal 85 now lighted, this signal displays one of the special indications referred to, which is known as an advance approach indication.

If, while the westbound train is approaching signal 88, trafic conditions west of signal 68 should change, so that relay 6D becomes energized and opens its contact it at the back point, relay utYLO and upper lamp Y of signal 58 will be deenergized. With contact it of relay 6D then closed at its front point, relay SGLO and lamp G of signal 58 will be energized b a circuit passing from terminal EB, through the front point of contact 9 of relay uBH, front point of contact IQ of relay 6D, winding of relay SGLO, and lamp G of signal (is to terminal EN.

With relay uBYLO deenergized, its contacts 36 and 34 will open the circuit previously traced for relay dBHD, causing relay cZ8I-ID to be deenergized. With relay dill-ID deenergized, lower lamp Y of signal 83 will be extinguished and lower lamp R of this signal will again be lighted.

With relay BGLO now energized, relay aSI-l'D will be energized by current of normal polarity in a circuit which is the same as the circuit previously traced for energizing this relay by current of reverse polarity except that it includes the front points of contacts 12 and I? of relay GGLO instead of the back points of these con' tacts. With relay u8HD energized by current of normal polarity, upper lamp G of signal as .will be lighted by a circuit passing from terminal EB, through the front point of contact I8 of relay u8HD, contact I9 of relay uiZl-ID closed in the normal position, and upper lamp G of signal 83 to terminal EN. With contact iii of relay uSHD now closed in the normal position, relay utLO and upper lamp Y of signal 8S will be deenergized. With upper lamp G and lower lamp R of signal 8S now lighted, this signal will display the clear indication.

I shall now assume that the westbound train moves over the stretch of track shown in the drawing, and that all parts of the apparatus are returned to the normal condition as shown inthe drawing. I shall assume further that switch W is then moved to its reverse position, and

that a leverman arranges for a westbound traffic movement over switch W in its reverse position by moving lever 6V to its r position.

With lever 6V in its r position and switch W in its reverse position, relay dBI-I becomes energized by a, circuit passing from terminal B, through contact of lever 6V, contact 26 of switch W in its reverse position, and the Winding of relay clEH to terminal N. With relay dSI-I energized, relay dGLO becomes energized, and the lower lamp Y of signal 6S becomes lighted, by a circuit passing from terminal EB, through the front point of contact H of relay dSI-l, winding of relay dBLO, and lower lamp Y to terminal EN. Signal 68, therefore, now displays the restricting indication shown by lighting upper lamp R over lower lamp Y.-

Relay u8HD is now energized by its reverse energizing circuit previously traced. Relay uBLO is therefore now energized, and upper lamp Y of signal 33 is lighted by the circuit previously traced.

I shall assume that a westbound train now approaches signal 88, deenergizing relays 'ITR and lI-ID as before. Relay 6A will therefore become deenergized as previously described. With relay (till now energized, relay 6F becomes energized by a second circuit, passing from terminal B, through contact 28 of relay (26H, contact 29 of relay 6A, and the winding of relay GP to terminal N.

With relay dSLO now energized, relay dBHD becomes energized by current of normalpolarity in a circuit which is the same as the circuitpreviously traced for this relay except that it includes the front points of contacts ill and 33 of relay dELO instead of the back points of these contacts and contacts 33 and 34 of relay utYLO. With relay cZBHD energizedby current of normal polarity, the lower lamp G of signal 8S becomes lighted by its circuit passing from terminal EB, through the front point of contact 20 of relay dEiHD, contact 23 of relay d8;HD closed in the normal position, and lower lamp G of signal 83 to terminal N. With upper lamp Y and lower lamp G ofsignal 88 now lighted, this signal displays another special indication, known as the approach medium indication.

I shall next assume that a leverman arranges for an eastbound trailic movement 'by placing lever 5V in its 1' position. Relay 5HR then becomes energized by its circuit passing from terr minal B, through contact 43 of lever 5V, and

the winding of relay EHR to terminal N.

Relay 5HR, upon becoming energized, opens its back contact 49, thereby causing relay 5ALS to e deenergized. Contact iii of relay EALS there- I upon opens the reverse energizing circuit previously traced for relay mil-ID, causing relay uBI-ID to be deenergized. With relay uBI-ID deenergized, its contact l8 opens at its front point, thereby extinguishing upper lamp Y of signal 8S. A circuit for lighting upper lamp R. of signal 88 is then closed through the back point of contact 18 of relay uBHD.

Relay 5H3, upon becoming energized, also opens its contact 39 at the back point, thereby extinguishing lamp R of signal 58. Contact 38 of relay iii-IR, upon becoming closed at its front point, completes a circuit for lighting lam-p G of signal 5S, this circuit passing from terminal EB, through the front point of contact 3%, front point of contact A l of relay EHD, contact 45 of relay HD closed in the normal position, and lamp G of signal ES to terminal EN.

When the leverman returns lever 5V to its n position, relay 5HR becomes deenergized. V Lamp G of signal SS is thereby extinguished, and lamp R of signal BS is again lighted. Also, contact A9 of relay 5BR becomes closed in circuit means for again energizing relay BALS.

When the eastbound train enters section b-'-c, relay SHD becomes deenergized by the opening of contacts 5 and 'l of relay BTR.

When the eastbound train enters section c-e, relay lTR becomes deenergized, and relay 'IHD is then deenergized by the opening of contact 35 of relay TIR. Contact 48 of relay ll-ID then opens at its front point, thereby extinguishing lamp G of signal is. Lamp R of signal 1S then becomes lighted by its circuit which includes the back point of contact 58 of relay II-ID.

Relay II-ID is slow releasing, and therefore its contact 31 remains closed at its front point for a brief period of time after relay ll-ID becomes deenergized. During this brief period of time, relay 18B is energized by a pickup circuit passing from terminal B, through contact 36 of relay ITR, front point of contact 31 of relay II-ID, and the winding of relay ISR, to terminal N. A stick circuit for relay 18R then becomes closed, passing from terminal B, through contact 36 of relay 'ITR, contact 38 of relay 18R, and the winding of relay ISR, to terminal N.

When the eastbound train leaves section b-c, relay 5HD becomes energized by current of re verse polarity passing from terminal lB, through the front point of contact 3 of relay TSR, contact I of relay 8TB, winding of relay til-ID, back point of contact 6 of relay 6F, contact 5 of relay 8TH, and the front point of contact 8 of relay 'lSR, to terminal IN. If lever 5V is then moved to its 7' position, so that relay 5HR is energized, lamp Y of signal 58 will be lighted by a circuit passing from terminal EB,through the front point of contact 39 of relay SHR, front point of contact 44 of relay 5H1), contact 45 of relay EHD in its reverse position, and lamp Y of signal 58, to terminal EN.

,Although I have herein shown and described only one form of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In a railway signal control system for signals for governing traffic movements in both directions over a stretch of railway track, including a home signal adjacent one end of said stretch for governing trafilc movements in a given direction off of said stretch and includinga distant signal adjacent the opposite end of said stretch for governing traffic movements in said given direction over said stretch toward said home signal and also including a third signal adjacent said home signal for governing traffic movements in the opposite direction over said stretch, the combination comprising, a traffic responsive relay which is normally energized but which becomes deenergized if a train approaches said distant signal in said given direction, a polarized signal relay for controlling said distant signal, an approach relay for said home signal, a transfer relay, a circuit controlledby a front contact of said trafilc responsive relay and by a back contact of said transfer relay for energizing said approach relay, means for at times controlling said home'sign'al to display a given indication and for at other times controlling said home signal to display a second indication, circuit means controlled by said trafiic responsive relay in its deenergized condition and by said transfer relay in its energized condition for energizing said polarized signal relay by current of normal or reverse polarity according as said home signal is controlled to display said given indication or said second indication respectively, a circuit controlled by a back contact of said approach relay for energizing said transfer relay if said home signal is controlled to display either said given indication of said second indication, and means including a back contact of said transfer relay for controlling said third signal.

2. In a railway signal control system for signals for governing traflic movements in both directions over a stretch of railway track, including a home signal adjacent one end of said stretch for governing trafiic movements in 'a given direction off of said stretch and including a distant signal adjacent the opposite end ofsaid stretch for governing traffic movements in said given direction over said stretch toward said home signal and also including a third signal adjacent said home signal for governing tramc movements in the opposite direction over said stretch and including a fourth signal adjacent said distant signal for also governing traflic movements in said opposite direction, the combination comprising, a track relay and a signal control relay for said fourth signal both of which are normally energized but which become deenergized if a train approaches said fourth signal in said given direction, a polarized signal relay for controlling said distant signal, an approach relay for said home signal, a transfer relay, a circuit controlled by a front contact of said track relay and by a back contact of said transfer relay for energizing said approach relay, means for at times controlling said home signal to display a given indication and for at other times controlling said home signal to display a second indication, circuit means controlled by back contacts of said track relay and said signal control relay and by said transfer relay in its energized condition for energizing said polarized signal relay by current of normal or reverse polarity according as said home signal is controlled to display said first or said second indication respectively, a circuit controlled by a back contact of said approach relay for energizing said transfer relay if said home signal is controlled to display either said first or said second indication, and means including a back contact of said transfer relay for controlling said third signal.

3. In a railway signal control system for signals for governing trafiic movements in both directions over a stretch of-railway tracks, including a home signal adjacent one end of said stretch for governing trafiic movements in a given direction off of said stretch and including a distant signal adjacent the opposite end of said stretch for governing trafiic movements in said given direction over said stretch toward said home signal and also including a third signal adjacent said home signal for governing traffic movements in the opposite direction over said stretch and including a fourth signal-adjacent said distant signal for also governing traffic movements in said opposite direction. the

combination comprising, a traflic responsive relay for controlling said fourth signal and which is normally energized but which becomes deenergized if a train approaches said fourth signal in said given direction, a stick relay which becomes energized if a train passes said fourth signal in said opposite direction and which then remains energized while said traffic responsive relay is deenergized, a signal relay for controlling said distant signal, an approach relay, a transfer relay, a circuit controlled by said stick relay and by said transfer relay both in the deenergized condition and by said traflic responsive relay in its energized condition for energizing said approach relay, means for at times controlling said home signal to display a given indication, a circuit controlled by a back contact of said approach relay for energizing said transfer relay if said home signal is controlled to display said given indication, and a circuit controlled by said traffic responsive relay in the deenergized condition and by said transfer relay in the energized condition for energizing said signal relay if said home signal is displaying said given indication.

4. In a railway signal control system for sig nals for governing traffic movements over a given stretch of railway track, including a home signal adjacent one end of said stretch for governing traflic movements in a given direction off of said stretch and including a distant signal adjacent the opposite end of said stretch for governing traffic movements in said given direction over said stretch toward said home signal, the combination comprising, a traflic responsive relay which is normally energized but which becomes deenergized if a train approaches said distant signal in said given direction, a signal relay for controlling said distant signal, an approach relay, a transfer relay, a circuit controlled by a front contact of said traffic responsive relay and by a back contact of said transfer relay for energizing said approach relay, means for at times controlling said home signal to display a given indication, a circuit controlled by a back contact of said approach relay for energizing said transfer relay if said home signal is controlled to display said given indication, and a circuit controlled by a back contact of said trafiic responsive relay and by a front contact of said transfer relay for energizing said signal relay if said home signal is controlled to display said given indication.

5. In a railway signal control system for signals for governing traffic movements in both directions over a stretch of railway track, including a home signal adjacent one end of said stretch for governing trafiic movements in a given direction oif of said stretch and including a distant signal adjacent the opposite end of said stretch for governing trafiic movements in said given direction over said stretch toward said home signal and also including a third signal adjacent said home signal for governing traflic movements in r the opposite direction over said stretch, the combination comprising, a trafiic responsive relay which is normally energized but which becomes deenergized if a train approaches said distant signal in said given direction, a signal relay for controlling said distant signal, an approach relay, a transfer relay, a circuit controlled by a front contact of said traflic responsive relay and by a back contact of said transfer relay for energizing said approach relay, means for at times controlling said home signal to display a given indication, a, circuit controlled by a back contact of said traflic responsive relay and by a front contact of said transfer relay for energizing said signal relay if said home signal is controlled to display said given indication, a circuit controlled by a back contact of said approach relay for energizing said transfer relay if said home signal is controlled to display said given indication, and means including a back contact of said transfer relay for controlling said third signal.

6. In a railway signal control system for signals for governing trafiic movements in both directions over a stretch of railway track, including a home signal adjacent one end of said stretch for governing traffic movements in a given direction off of said stretch and including a distant signal adjacent the opposite end of said stretch for governing traffic movements in said given direction over said stretch toward said home signal and also including a third signal adjacent said home signal for governing trafiic movement in the opposite direction over said stretch, the combination comprising, a traflic responsive relay which is normally energized but which becomes deenergized if a train approaches said distant signal in said given direction, an approach relay, a transfer relay, a circuit controlled by a front contact of said trafiic responsive relay and by a back contact of said transfer relay and also by traffic conditions between said home and distant signals for controlling said approach relay, a circuit controlled by a back contact of said trafiic responsive relay and by a front contact of said transfer relay for controlling said distant signal, a circuit controlled by a back contact of said approach relay and by control means for said home signal for energizing said transfer relay, and means including a back contact of said transfer relay for controlling said third signal.

7. In a railway signal control system for signals for governing traflic movements over a given stretch of railway track, including a home signal adjacent one end of said stretch for governing trafiic movements in a given direction off of said stretch and including a distant signal adjacent the opposite end of said stretch for governing trafiic movements in said given direction over said stretch toward said home signal, the combination comprising, a traffic responsive relay which is normally energized but which becomes deenergized if a train approaches said distant signal in said given direction, an approach relay, a transfer relay, a circuit controlled by a front contact of said traffic responsive relay and by a back contact of said transfer relay for energizing said approach relay, a circuit controlled by a back contact of said approach relay and by control means for said home signal for energizing said transfer relay, and means controlled by a back contact of said traflic responsive relay and by a front contact of said transfer relay for controlling said distant signal.

PHILLIP F. HOLDEN.

- REFERENCES CITED UNITED STATES PATENTS Name Date Rees July 18, 1944 Number 

